Area Hydrologic Discussion
— Latest
Threat
POTENTIAL IMPACTS: Flash and urban flooding WHERE: Southeastern Nebraska, northeastern Kansas, northwestern WHEN: Through early Thursday morning
Rainfall & Conditions
QPF: 1 - 3", locally 4+" (HRRR/RRFS/WPC) Rainfall Rates: 1 - 2"/hr, locally higher (HRRR/RRFS/WPC) Relative Soil Moisture: 10 - 60% RSM (SPoRT 0 - 10 cm) Streamflows: Normal to above normal (observed, USGS)
Discussion
Heavy thunderstorms ongoing across the area of concern will continue to expand in coverage and intensity across the area of concern into the overnight hours, potentially generating flash and urban flooding impacts.. Central Iowa is most hydrologically vulnerable across the area of concern given wetter soils and elevated streamflows from repeated rounds of rainfall over the past week. As such, given the potential for intense rainfall rates and training/repeating storms, rainfall will immediately runoff into streams and rivers with reduced in-channel storage and lead to flash and urban flooding. Elsewhere across the region, impacts will be more localized and dependent on rainfall intensity. Rapid rises on quick-responding streams/creeks are possible, especially in urbanized areas.
The HRRR-forced National Water Model (NWM) is highlighting the potential for small stream responses across the area of concern along the Kansas/Nebraska border and across western and central Iowa, with peak flows expected during the overnight hours. Corresponding annual exceedance probabilities are not overly impressive, as the latest High Flow Magnitude Forecast is indicating probabilities at or greater than 50%. However, there are some AEPs of 20% and lower across portions of Iowa and along the Kansas/Nebraska border, which suggests some locally significant small stream rises are possible. Widespread significant impacts aren't expected, although they cannot be entirely ruled out given the likelihood of training convection and robust rainfall rates.
Addressed To
WFO: DMX, FSD, OAX, GID, ICT, TOP RFC: TUA, KRF, MSR, WPC
000 AGUS74 KWCO 090120 AHDNWC Area Hydrological Discussion #137 - EXPERIMENTAL NWS National Water Center - Tuscaloosa, AL 812 PM CDT Wed Jul 08 2026 POTENTIAL IMPACTS: Flash and urban flooding WHERE: Southeastern Nebraska, northeastern Kansas, northwestern Missouri, and western/central Iowa WHEN: Through early Thursday morning FORECAST RAINFALL AND ANTECEDENT CONDITIONS... QPF: 1 - 3", locally 4+" (HRRR/RRFS/WPC) Rainfall Rates: 1 - 2"/hr, locally higher (HRRR/RRFS/WPC) Relative Soil Moisture: 10 - 60% RSM (SPoRT 0 - 10 cm) Streamflows: Normal to above normal (observed, USGS) DISCUSSION... Heavy thunderstorms ongoing across the area of concern will continue to expand in coverage and intensity across the area of concern into the overnight hours, potentially generating flash and urban flooding impacts.. Central Iowa is most hydrologically vulnerable across the area of concern given wetter soils and elevated streamflows from repeated rounds of rainfall over the past week. As such, given the potential for intense rainfall rates and training/repeating storms, rainfall will immediately runoff into streams and rivers with reduced in-channel storage and lead to flash and urban flooding. Elsewhere across the region, impacts will be more localized and dependent on rainfall intensity. Rapid rises on quick-responding streams/creeks are possible, especially in urbanized areas. The HRRR-forced National Water Model (NWM) is highlighting the potential for small stream responses across the area of concern along the Kansas/Nebraska border and across western and central Iowa, with peak flows expected during the overnight hours. Corresponding annual exceedance probabilities are not overly impressive, as the latest High Flow Magnitude Forecast is indicating probabilities at or greater than 50%. However, there are some AEPs of 20% and lower across portions of Iowa and along the Kansas/Nebraska border, which suggests some locally significant small stream rises are possible. Widespread significant impacts aren't expected, although they cannot be entirely ruled out given the likelihood of training convection and robust rainfall rates. GRAPHICAL REPRESENTATION: weather.gov/owp/operations-ahd Additional National Water Center products are available at: weather.gov/owp/operations //JDP ATTN...WFO...DMX...FSD...OAX...GID...ICT...TOP... EAX...DVN ATTN...RFC...TUA...KRF...MSR...WPC